“It is Texas A&M’s longstanding practice not to respond to such questions concerning specific student-athletes,” Texas A&M's associate athletics director Jason Cook said in a statement.

According to Outside the Lines sources, Manziel agreed to a five-figure flat fee to sign photographs, footballs, mini helmets and other items at the request of autograph broker Drew Tieman while at the BCS Championship Game in Miami in January.

Witnesses told Outside the Lines that they witnessed Manziel signing the items, but never saw an exchange of money. They also said that Manziel went to Tieman’s home to sign items before leaving Miami.

Nate Fitch, a friend of Manziel's, posted several tweets at that time saying he was with the Heisman winner in South Florida for the BCS title game. None of Fitch's tweets around the dates of that trip suggested anything about meeting with Tieman, or any memorabilia signings.

Tieman's Facebook page was taken down Sunday night, but cached images collected from the page included a photo of him and Notre Dame's Manti Te'o, which was purportedly taken Jan. 3, less than a week before the BCS game.

Manziel rose to prominence last season as he became the first player to win the Heisman Trophy as a freshman. His signature moment came when he led Texas A&M to an upset win over then-No. 1 Alabama last November.